IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specification for implementing wireless local area network (WLAN) computer communication in the Wi-Fi (2.4, 3.6, 5, and 60 GHz) frequency bands. The standards and amendments provide the basis for wireless network products using the Wi-Fi frequency bands. For example, IEEE 802.11ac is a wireless networking standard in the 802.11 family providing high-throughput WLANs on the 5 GHz band. Significant wider channel bandwidths (20 MHz, 40 MHz, 80 MHz, and 160 MHz) were proposed in the IEEE 802.11ac standard. The High Efficiency WLAN study group (HEW SG) is a study group within IEEE 802.11 working group that will consider the improvement of spectrum efficiency to enhance the system throughput in high-density scenarios of wireless devices. Because of HEW SG, TGax was formed and tasked to work on IEEE 802.11ax standard that will become a successor to IEEE 802.11ac.
IEEE 802.11ax is seeking throughput enhancement in the dense deployed environment. Specifically, uplink (UL) and downlink (DL) user aggregation has been introduced to increase network efficiency. UL orthogonal frequency division multiple access (OFDMA) has significantly higher spectral density (narrower bandwidth), which might increase overlapping basic service set (OBSS) interference. For OFDMA and multi-user multiple input and multiple output (MU-MIMO), UL timing synchronization is required and the duration of UL and DL PPDU TX times are controlled by the access point (AP) of each BSS.
For APs deployed in managed network or by carrier operator, it is possible to have AP-AP information exchange. Possible AP-AP information exchange methods may include wired communication between AP-AP such as through Internet or in a wired local network; APs co-located with LTE base stations are connected through the cellular backbone network; and AP-AP connected via wireless link in different bands/channels.
There are different BSS overlapping geometries and hence different types of OBSS interferences. Based on the different OBSS interference types, a solution for OBSS interference mitigation is sought.